Evaluation of the influenza sentinel surveillance system in the Democratic Republic of Congo, 2012-2015.

BACKGROUND: The World Health Organization recommends periodic evaluations of influenza surveillance systems to identify areas for improvement and provide evidence of data reliability for policymaking. However, data about the performance of established influenza surveillance systems are limited in Africa, including in the Democratic Republic of Congo (DRC). METHODS: We used the Centers for Disease Control and Prevention guidelines to evaluate the performance of the influenza sentinel surveillance system (ISSS) in DRC during 2012-2015. The performance of the system was evaluated using eight surveillance attributes: (i) data quality and completeness for key variables, (ii) timeliness, (iii) representativeness, (iv) flexibility, (v) simplicity, (vi) acceptability, (vii) stability and (viii) utility. For each attribute, specific indicators were developed and described using quantitative and qualitative methods. Scores for each indicator were as follows: < 60% weak performance; 60-79% moderate performance; ≥80% good performance. RESULTS: During 2012-2015, we enrolled and tested 4339 patients with influenza-like illness (ILI) and 2869 patients with severe acute respiratory illness (SARI) from 11 sentinel sites situated in 5 of 11 provinces. Influenza viruses were detected in 446 (10.3%) samples from patients with ILI and in 151 (5.5%) samples from patients with SARI with higher detection during December-May. Data quality and completeness was > 90% for all evaluated indicators. Other strengths of the system were timeliness, simplicity, stability and utility that scored > 70% each. Representativeness, flexibility and acceptability had moderate performance. It was reported that the ISSS contributed to: (i) a better understanding of the epidemiology, circulating patterns and proportional contribution of influenza virus among patients with ILI or SARI; (ii) acquisition of new key competences related to influenza surveillance and diagnosis; and (iii) continuous education of surveillance staff and clinicians at sentinel sites about influenza. However, due to limited resources no actions were undertaken to mitigate the impact of seasonal influenza epidemics. CONCLUSIONS: The system performed overall satisfactorily and provided reliable and timely data about influenza circulation in DRC. The simplicity of the system contributed to its stability. A better use of the available data could be made to inform and promote prevention interventions especially among the most vulnerable groups.

Epidemiology of circulating human influenza viruses from the Democratic Republic of Congo, 2015.

INTRODUCTION: The establishment of the influenza sentinel surveillance system in Kinshasa, Bas Congo, Maniema, Katanga, and Kasai Provinces allowed generation of important data on the molecular epidemiology of human influenza viruses circulating in the Democratic Republic of Congo (DRC). However, some challenges still exist, including the need for extending the influenza surveillance to more provinces. This study describes the pattern of influenza virus circulating in DRC during 2015. METHODOLOGY: Nasopharyngeal swabs were collected from January to December 2015 from outpatients with influenza-like illness (ILI) and in all hospitalized patients with Severe Acute Respiratory Infection (SARI). Molecular analysis was done to determine influenza type and subtype at the National Reference Laboratory (NRL) in Kinshasa using real time reverse transcription-polymerase chain reaction (rRT-PCR). Analysis of antiviral resistance by enzyme inhibition assay and nucleotide sequencing was performed by the Collaborating center in the USA (CDC, Atlanta). RESULTS: Out of 2,376 nasopharyngeal swabs collected from patients, 218 (9.1%) were positive for influenza virus. Among the positive samples, 149 were characterized as influenza virus type A (Flu A), 67 as type B (Flu B) and 2 mixed infections (Flu A and B). Flu A subtypes detected were H3N2 and H1N1. The Yamagata strain of Flu B was detected among patients in the country. Individuals aged between 5 and 14 years accounted for the largest age group affected by influenza virus. All influenza viruses detected were found to be sensitive to antiviral drugs such as oseltamivar, zanamivir, peramivir and laninamivar. CONCLUSION: The present study documented the possible involvement of both circulation of Flu A and B viruses in human respiratory infection in certain DRC provinces during 2015. This study emphasises the need to extend the influenza surveillance to other provinces for a better understanding of the epidemiology of influenza in DRC. It is envisioned that such a system would lead to improved disease control and patient management.

The national and provincial burden of medically attended influenza-associated influenza-like illness and severe acute respiratory illness in the Democratic Republic of Congo, 2013-2015.

BACKGROUND: Estimates of influenza-associated outpatient consultations and hospitalizations are severely limited in low- and middle-income countries, especially in Africa. METHODS: We conducted active prospective surveillance for influenza-like illness (ILI) and severe acute respiratory illness (SARI) at 5 healthcare facilities situated in Kinshasa Province during 2013-2015. We tested upper respiratory tract samples for influenza viruses using a reverse transcription-polymerase chain reaction assay. We estimated age-specific numbers and rates of influenza-associated ILI outpatient consultations and SARI hospitalizations for Kinshasa Province using a combination of administrative and influenza surveillance data. These estimates were extrapolated to each of the remaining 10 provinces accounting for provincial differences in prevalence of risk factors for pneumonia and healthcare-seeking behavior. Rates were reported per 100 000 population. RESULTS: During 2013-2015, the mean annual national number of influenza-associated ILI outpatient consultations was 1 003 212 (95% Confidence Incidence [CI]: 719 335-1 338 050 - Rate: 1205.3; 95% CI: 864.2-1607.5); 199 839 (95% CI: 153 563-254 759 - Rate: 1464.0; 95% CI: 1125.0-1866.3) among children aged <5 years and 803 374 (95% CI: 567 772-1 083 291 - Rate: 1154.5; 95% CI: 813.1-1556.8) among individuals aged ≥5 years. The mean annual national number of influenza-associated SARI hospitalizations was 40 361 (95% CI: 24 014-60 514 - Rate: 48.5; 95% CI: 28.9-72.7); 25 452 (95% CI: 19 146-32 944 - Rate: 186.5; 95% CI: 140.3-241.3) among children aged <5 years and 14 909 (95% CI: 4868-27 570 - Rate: 21.4; 95% CI: 28.9-72.7) among individuals aged ≥5 years. CONCLUSIONS: The burden of influenza-associated ILI outpatient consultations and SARI hospitalizations was substantial and was highest among hospitalized children aged <5 years.

Molecular Analysis of Influenza A(H3N2) and A(H1N1)pdm09 Viruses circulating in the Democratic Republic of Congo, 2014.

BACKGROUND: Very little is known about influenza viruses circulating in the Democratic Republic of Congo (DRC). We aim to characterize genetically and antigenically Influenza A(H3N2) and A(H1N1)pdm09 viruses circulating in the country. METHODS: From August to December 2014, specimens were collected from patients with influenza like-illness (ILI) or severe acute respiratory infection (SARI) in various surveillance sites. Specimens were tested using real time reverse transcription polymerase chain reaction (RT-PCR) method for the detection of influenza viruses. Positive influenza samples with a cycle threshold (Ct) <30 were genetically and antigenically characterized. RESULTS: 32 samples tested were found positive to influenza A with Ct <30. At CDC Atlanta, 28 out of 32 samples (88%) were tested positive for influenza A virus, including 26 seasonal influenza A viruses subtype H3N2 and 2 pandemic influenza A viruses subtype H1N1pdm 2009. The majority of influenza A(H3N2) viruses were antigenically related to the A/Switzerland/9715293/2013 vaccine virus, while two influenza A(H1N1)pdm09 isolates were antigenically characterized as A/California/07/2009-like. All A(H3N2) and A(H1N1)pdm09 virus isolates characterized were sensitive to oseltamivir and zanamivir. CONCLUSION: Two genetically distinct influenza subtypes were co-circulating in the DRCongo. Effective measures against influenza have been suggested.